Story so far. I've been through a lot of self help stuff, but still getting nowhere. Just want to see if anyone has got any further info that could help me. HD had snow leopard on it. I've reset pram, Checked battery, removed all external devices, tried to boot in safe etc. didnt work. I have external CD tried to boot from that - no go. Removed internal superdrive as it was always a bit flaky - didn't help. Stuck in a fresh HD and tried to boot from CD - no worky. I did get into single user and run FSCK -F or whatever it was - was ok. On original HD BTW. Whatever I seem to do apart from FSCK, it seems to hang after a little while and the wheel stops a spinning, with fresh HD and boot from external CD it takes about 30 seconds maybe a little longer then I get slow grey screen swipe every time. Behind the drives there are what looks like thermal sensors - could it be them? Will probably just keep unplugging stuff now till I see a difference. Any help will be appreciated.